The present invention relates generally to a dye laser amplifier of the type in which a continuously replenished supply of dye is excited with a first light beam in order to amplify the intensity of a second, different light beam passing through the continuously replenished dye. The present invention relates more particularly to a pair of specifically configured windows through which the second beam passes as the latter enters and exits the amplifier's dye cell containing the continuously replenished supply of dye.
A typical dye laser amplifier includes means defining the last mentioned dye cell through which a continuous stream of lasing dye is caused to pass a series of transparent windows into the chamber. Means are provided for directing the first beam or more than one such beam into the cell through cooperating windows while, at the same time, the second dye beam is caused to pass into and out of the same cell through its own cooperating windows.
In a dye laser amplifier of the general type just described, the pressure within its dye cell can be quite large when the amplifier is operated at relatively high flow rates and velocities. Therefore, the windows into this cell must be structurally sound, that is, they must be able to withstand the internal pressures therein without breaking, leaking or even deforming. This can be accomplished quite readily by making the windows relatively thick. However, the thicker the windows are made the more heat they tend to absorb from the passing light beams. At the same time, as the windows increase in temperature their refractive properties tend to change. In the case of those windows which serve to pass the dye beam, this change results in a lens effect which distorts the optical characteristics of the dye beam in a corresponding way.
One possible solution to the "window thickness" problem recited above is to make the dye beam windows only large enough to pass the dye beam itself. In this way, the windows could be made thinner than would be possible if they were substantially larger in surface area than the cross section of the dye beam. However, because the window, which is typically glass, is constructed of a different material than the rest of the dye cell defining means which forms part of the overall amplifier, a material-to-material juncture would be present within or in very close proximity to the cell. This, in turn, could result in undesired flow within the cell, as discussed in more detail in copending application Ser. No. 911,271, filed Sep. 22, 1986 and entitled HIGH FLOW VELOCITY DYE LASER AMPLIFIER. On the other hand, it may not be possible to make a larger window of the type in this application as thin as it should be without causing it to leak or fracture or even merely deform which could result in optical distortion of the dye beam passing therethrough.